batch operations

Cargo.lock

@@ -8,6 +8,12 @@ version = "1.0.1"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "cdb031dd78e28731d87d56cc8ffef4a8f36ca26c38fe2de700543e627f8a464a"
 
+[[package]]
+name = "cfg-if"
+version = "1.0.0"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "baf1de4339761588bc0619e3cbc0120ee582ebb74b53b4efbf79117bd2da40fd"
+
 [[package]]
 name = "futures"
 version = "0.3.16"
@@ -102,13 +108,31 @@ dependencies = [
  "slab",
 ]
 
+[[package]]
+name = "getrandom"
+version = "0.2.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "7fcd999463524c52659517fe2cea98493cfe485d10565e7b0fb07dbba7ad2753"
+dependencies = [
+ "cfg-if",
+ "libc",
+ "wasi",
+]
+
 [[package]]
 name = "hypoloop"
 version = "0.1.0"
 dependencies = [
  "futures",
+ "rand",
 ]
 
+[[package]]
+name = "libc"
+version = "0.2.99"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "a7f823d141fe0a24df1e23b4af4e3c7ba9e5966ec514ea068c93024aa7deb765"
+
 [[package]]
 name = "memchr"
 version = "2.4.0"
@@ -127,6 +151,12 @@ version = "0.1.0"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8b870d8c151b6f2fb93e84a13146138f05d02ed11c7e7c54f8826aaaf7c9f184"
 
+[[package]]
+name = "ppv-lite86"
+version = "0.2.10"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "ac74c624d6b2d21f425f752262f42188365d7b8ff1aff74c82e45136510a4857"
+
 [[package]]
 name = "proc-macro-hack"
 version = "0.5.19"
@@ -157,6 +187,46 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "rand"
+version = "0.8.4"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "2e7573632e6454cf6b99d7aac4ccca54be06da05aca2ef7423d22d27d4d4bcd8"
+dependencies = [
+ "libc",
+ "rand_chacha",
+ "rand_core",
+ "rand_hc",
+]
+
+[[package]]
+name = "rand_chacha"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "e6c10a63a0fa32252be49d21e7709d4d4baf8d231c2dbce1eaa8141b9b127d88"
+dependencies = [
+ "ppv-lite86",
+ "rand_core",
+]
+
+[[package]]
+name = "rand_core"
+version = "0.6.3"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d34f1408f55294453790c48b2f1ebbb1c5b4b7563eb1f418bcfcfdbb06ebb4e7"
+dependencies = [
+ "getrandom",
+]
+
+[[package]]
+name = "rand_hc"
+version = "0.3.1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "d51e9f596de227fda2ea6c84607f5558e196eeaf43c986b724ba4fb8fdf497e7"
+dependencies = [
+ "rand_core",
+]
+
 [[package]]
 name = "slab"
 version = "0.4.3"
@@ -179,3 +249,9 @@ name = "unicode-xid"
 version = "0.2.2"
 source = "registry+https://github.com/rust-lang/crates.io-index"
 checksum = "8ccb82d61f80a663efe1f787a51b16b5a51e3314d6ac365b08639f52387b33f3"
+
+[[package]]
+name = "wasi"
+version = "0.10.2+wasi-snapshot-preview1"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fd6fbd9a79829dd1ad0cc20627bf1ed606756a7f77edff7b66b7064f9cb327c6"

Cargo.toml

@@ -7,3 +7,4 @@ edition = "2018"
 
 [dependencies]
 futures = "0.3.16"
+rand = "0.8.4"

src/main.rs

@@ -1,4 +1,5 @@
 use std::time::{Duration, Instant};
+use rand::Rng;
 
 // loop constants
 const UPDATE_INTERVAL: u32 = 40;
@@ -8,8 +9,9 @@ const DEBUG_LOOP: bool = false;
 const GRAVITY: f32 = -9.8;
 
 // a struct made for physics objects
-#[derive(Copy, Clone)]
+#[derive(Clone)]
 struct PhysicsObject {
+    name: String,
 	location: [f32; 3],
 	velocity: [f32; 3],
     gravity_enabled: bool
@@ -24,27 +26,36 @@ fn main() {
     // track the delta time (the duration of the previous loop in milliseconds)
     let mut delta_time = Duration::new(0, 0);
     
-    // create a test physics object
+    // a vector of objects to calculate physics for
-    let mut test_object = PhysicsObject {
+    let mut objects: Vec<PhysicsObject> = vec![];
-        location: [0.0, 0.0, 10.0],
+    let mut rng = rand::thread_rng();
-        velocity: [0.0, 5.0, 0.0],
+    for i in 0..6 {
+        let new_object = PhysicsObject {
+            name: i.to_string(),
+            location: [0.0, 0.0, 0.0],
+            velocity: [rng.gen::<f32>() * 10.0, rng.gen::<f32>() * 10.0, rng.gen::<f32>() * 10.0],
             gravity_enabled: true
         };
 
+        objects.push(new_object)
+    }
+
     while simulate {
         // start timing the loop
         let start_time = Instant::now();
 
         // update
         if delta_time.as_millis() as u32 >= UPDATE_INTERVAL {
-            update(delta_time, &mut test_object);
+            update(delta_time, &mut objects);
             
             // reset the delta time
             delta_time = Duration::new(0,0);
         }
         
         // DEBUG
-        println!("Time: {}s | test_object | Location: {:?} | Velocity: {:?}", time.as_millis() as f32 / 1000.0, test_object.location, test_object.velocity);
+        for object in objects.iter() {
+            println!("Time: {}s | {} | Location: {:?} | Velocity: {:?}", time.as_millis() as f32 / 1000.0, object.name, object.location, object.velocity);
+        }
         
         //display(delta_time, &test_object);
         
@@ -57,7 +68,7 @@ fn main() {
 
 // update function
 // TODO - I think I'm resetting delta time in the wrong place or just using it incorrectly; frameskips aren't happening at all
-fn update(delta_time: Duration, object: &mut PhysicsObject) {
+fn update(delta_time: Duration, objects: &mut Vec<PhysicsObject>) {
     if DEBUG_LOOP {
         println!("Updating");
     }
@@ -65,14 +76,19 @@ fn update(delta_time: Duration, object: &mut PhysicsObject) {
     // calculate the exact timestep (fractional time in seconds) from delta time
     let timestep: f32 = delta_time.as_millis() as f32 / 1000.0;
     
+    for object in objects.iter_mut() {
         // update location based on velocity
         for i in 0..3 {
-        object.location[i] += timestep * object.velocity[i];
+            // location += timestep * velocity
+            // use an FMA here to halve the rounding error
+            object.location[i] = timestep.mul_add(object.velocity[i], object.location[i]);
         }
     
         // gravity
         if object.gravity_enabled {
-        object.velocity[2] += GRAVITY * timestep;
+            // velocity += timestep * gravity
+            // use an FMA here to halve the rounding error
+            object.velocity[2] = timestep.mul_add(GRAVITY, object.velocity[2]);
         }
     
         // prevent the object from going below the ground plane, and kill downward velocity upon "hitting" the ground plane
@@ -80,6 +96,7 @@ fn update(delta_time: Duration, object: &mut PhysicsObject) {
             object.location[2] = 0.0;
             object.velocity[2] = object.velocity[2].max(0.0);
         }
+    }
 }
 
 // render function
@@ -92,14 +109,6 @@ fn display(delta_time: Duration, object: &PhysicsObject) {
         println!("Displaying | Delta Time: {}ms | Relative Time: {}", delta_time.as_millis(), interpolation);
     }
 
-    // create a "render object", which we can apply interpolation to
-    let mut render_object = *object;
-
-    // interpolate physics values for smooth rendering
-    for i in 0..3 {
-        render_object.location[i] += render_object.velocity[i] * interpolation;
-    }
-
     // DEBUG
     // println!("test_object | Location: {:?} | Velocity: {:?}", render_object.location, render_object.velocity);
 }